Multi GNSS PPP analysis on SWEPOS reference stations
Typ
Examensarbete för masterexamen
Program
Publicerad
2021
Författare
Jäverbrink, Erik
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
The Swedish mapping, cadastral and land registration authority, Lantmäteriet,
has a permanent network of GNSS stations, SWEPOS, which
can be used as reference stations in differencing and RTK. A limiting
factor in the RTK service is, or soon will be, related to local, station
dependent effects. This study has utilized the carrier phase residuals for
GPS and Galileo from the multi-GNSS PPP software GipsyX to analyze
the surrounding environment and local effects around 42 SWEPOS stations.
21 of the stations are concrete pillars and 21 are steel grid masts
and there exists one of each at each of the locations, which ranges from
the southern part of Sweden to the north. The carrier phase residuals
were successfully utilized to describe local phenomena such as wooden
fences, adjacent houses and multipath from solid bedrock. There was
however an effect that was only present for one station, VIS6, that could
not be explained. Its residuals at high elevation, 45° - 90°, followed
those of the elevation angle circles instead of the satellites’ orbits. It was
illustrated and shown with examples that it is useful to analyze stations
in pairs. It helps to discredit certain error sources and phenomena that
should be affecting both of the stations. It was furthermore illustrated
that it is useful to study the monthly mean residuals as a function of
elevation angle in parallel with the skyplots. The steel grid mast stations
were furthermore analyzed with respect to coordinate repeatability
and it was found that the highest performance were achieved with the
combination of GPS+GLONASS+Galileo. The achieved repeatabilities
(standard deviation) for the latitudinal, longitudinal and vertical components
were 1.20mm, 3.56mm and 4.00mm, respectively. The coordinate
accuracies for GPS, GPS+Galileo and GPS+GLONASS were within
the GPS+GLONASS+Galileo repeatability. Their respective repeatabilities
differs to that of GPS+GLONASS+Galileo by sub-millimeter levels,
which means that any of the combinations yields comparable results.
Beskrivning
Ämne/nyckelord
GNSS, PPP, GipsyX, repeatability, solution offsets, carrier phase residuals, multipath.